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    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
      /* 视口  v(viewport) 
      
      vw： viewport  width  平分为100等分 1vw  1/100
      vh： viewport  height

      px  =>   vw /  vh
    
      假设视口:  375     320 
      1vw = 3.75px       1vw = 3.2px
      
      
      */
      *{margin: 0;padding: 0;}
      .box{
          width:10vw;
          height:10vw;
          background-color: green;
      }
    </style>
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<body>
    <div class="box"></div>
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